Medical access devices, particularly infusion devices, over-the-needle catheters, other catheters and feeding tubes are important tools for administration of fluids to patients. After placement, in normal management of a catheter or other medical access device in a patient, it is often necessary to be able to add or withdraw fluids through the device. In many surgical procedures, it is routine to place an intravenous catheter so that if it is necessary to medicate a patient during a procedure, the catheter already is in place. In other types of procedures it is necessary to periodically administer medicaments through the device or to withdraw samples. In all of these applications, the presence of a valve mechanism on the device to facilitate the addition and to close the device after the addition is desirable.
U.S. Pat. No. 4,512,766 discloses an intravenous catheter assembly with a valve located in the catheter hub made of needle-penetrable self-sealing material such as an elastomeric cap with a closed end. The valve disclosed in the patent is biased to a closed position wherein it surrounds an open inlet end of a hollow elongated insert tube disposed in the hub. The valve may be opened by positioning a male luer adapter onto the assembly. The male luer adapter forces the elastomeric cap to slide longitudinally along the insert tube past the insert tube open end. As the elastomeric cap moves, a puncture or slit previously placed in the wall of the closed end of the elastomeric cap expands over the insert tube open end as the cap is collapsed axially. The insert tube open end then projects into the male luer adapter so that fluid may pass into the insert tube. When the male adapter is removed, the compressed elastomeric cap expands and closes the puncture or slit over the open end of insert tube to close the valve.
U.S. Pat. No. 5,085,645 teaches an over-the-needle catheter having an integral valve in a passage in the catheter hub. The patent discloses a valve adapter that is an integral part of a catheter hub.
U.S. Pat. No. 5,251,873 teaches a medical coupling site that is adapted to be attached directly to a standard male luer lock fitting. The coupling site includes a valve element contained within a tubular retainer. The coupling site includes a slit rubber diaphragm valve that is deflected and opened by introduction of a male luer fitting and closed by the removal of the male luer. According to international standards, there is an allowable range of 2.5 mm in engagement length of a luer fitting. This variation in engagement length occurs because of variation in the outside diameter of the male projection and the inside diameter of the female receptacle of the luer fittings. Thus, a "fat" male luer results in a "short" engagement length and conversely. Valves of the type disclosed in U.S. Pat. No. 5,251,873 may not open fully with male luer fittings at the "short" end of the allowable dimension, and since they also depend on the diaphragm for sealing around the male luer tip, they may also leak when a male fitting is mounted or may not fully close once opened.
U.S. Pat. No. 5,108,380 discloses a valve device for a hub member of a catheter. The valve is actuated by the placement of a male luer fitting which displaces a piston biased by a coil spring to open the valve.
U.S. Pat. No. 5,269,771 discloses a needleless introducer with a hemostatic valve. The valve mechanism includes a plunger biased by a coil spring that, upon actuation, spreads a pair of resilient valve elements. A valve of the design disclosed in this patent may not be fully opened by a male luer fitting at the "short" side of the dimension, and the sealing depends upon the resilient valve elements closing against themselves. Further, the valve disclosed in this patent is composed of several different materials and is complex to assemble.
Valves and adapters of the type described above fall into a medical device category often referred to as "PRN" from the Latin pro re nata, i.e., as the circumstances may require. A typical example of usage for this type device is on a catheter left in place for three days. During this three day usage duration, a bolus dosage of a medicament might be given every 4 hours using a protocol including at each dosage interval: a) flushing the catheter to check patency; b) administration of the medicament; and c) flushing the medicament from the catheter with heparin or saline. During this typical usage period, this protocol results in 54 operations of the valve, i.e., 6 times a day, 3 steps each time and 3 days. Between each dosage the valve must not leak, but it must be readily reopened. Following the traditional technique, bolus introductions would have been made using hypodermic needles to penetrate a resilient septum. However, a septum is likely to start leaking after multiple penetrations and, given the concerns about risks to practitioners and service personnel from "sharps," hospitals have changed many protocols to reduce the use of pointed hypodermic needles. The PRN adapters as described above have been developed to address the hospitals' changing needs.
While the teachings cited above address many of the practitioners' concerns, there is still a need for a valved adapter for medical access devices that offers rapid, easy-to-use access with automatic positive on/off flow control. Additionally, many of the currently available adapters are open at the proximal end requiring an additional plug or cover to avoid contamination of the fitting when a fluid delivery device is not mounted. A device having these features plus the advantage of being self closing, easily cleanable and simple to manufacture is disclosed herein.